Orchard variable-rate spraying method integrating GNSS and wind-excited audio-conducted leaf area density

IntroductionConventional air-assisted sprayers used in orchards often suffer from excessive pesticide waste, high residue levels, and uneven droplet distribution on fruit tree canopies. Precision spraying technologies have emerged to address these limitations by enabling dynamic regulation of spray...

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Main Authors: Hangxing Zhao, Shenghui Yang, Wenwei Li, Han Feng, Shijie Jiang, Weihong Liu, Jingbin Li, Yongjun Zheng, Songchao Zhang
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-07-01
Series:Frontiers in Plant Science
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Online Access:https://www.frontiersin.org/articles/10.3389/fpls.2025.1621080/full
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author Hangxing Zhao
Hangxing Zhao
Hangxing Zhao
Shenghui Yang
Shenghui Yang
Shenghui Yang
Wenwei Li
Wenwei Li
Han Feng
Han Feng
Shijie Jiang
Shijie Jiang
Weihong Liu
Weihong Liu
Jingbin Li
Yongjun Zheng
Yongjun Zheng
Songchao Zhang
author_facet Hangxing Zhao
Hangxing Zhao
Hangxing Zhao
Shenghui Yang
Shenghui Yang
Shenghui Yang
Wenwei Li
Wenwei Li
Han Feng
Han Feng
Shijie Jiang
Shijie Jiang
Weihong Liu
Weihong Liu
Jingbin Li
Yongjun Zheng
Yongjun Zheng
Songchao Zhang
author_sort Hangxing Zhao
collection DOAJ
description IntroductionConventional air-assisted sprayers used in orchards often suffer from excessive pesticide waste, high residue levels, and uneven droplet distribution on fruit tree canopies. Precision spraying technologies have emerged to address these limitations by enabling dynamic regulation of spray parameters according to canopy characteristics. Among these, leaf area density is a key indicator for describing canopy sparseness. However, accurate and automated measurement of canopy leaf area density remains challenging due to leaf shading effects. As a result, few fully functional variable-rate spraying systems have been developed based on this parameter.MethodsThis study presents a variable-rate spraying method that integrates global navigation satellite system (GNSS) positioning with wind-excited audio-conducted estimation of canopy leaf area density. A self-propelled orchard spraying platform was developed to acquire real-time GNSS positioning and audio-conducted canopy leaf area density data. Based on this, a method was established for generating prescription maps that integrate spatial positioning and canopy density information. A variable-rate spray control model and algorithm were then constructed to regulate spray flow according to the spatial distribution of leaf area density across the orchard.ResultsField experiments demonstrated that the system achieved a mean relative error of only 5.52% in spray flow rate regulation. Compared with conventional constant-rate spraying, the variable-rate mode reduced the longitudinal coefficient of variation (CV) of droplet deposition by 55.75% on adaxial leaf surfaces and by 33.22% on abaxial surfaces, with a maximum reduction of 62.32% in transverse CV. Ground runoff of spray solution was reduced by 62.29%, and droplet deposition density on leaf surfaces exceeded 25 droplets/cm², meeting the standard for low-volume insecticide application.DiscussionThe integration of GNSS and wind-excited audio sensing for real-time canopy density assessment enables more precise and efficient pesticide application in orchards. This system significantly improves droplet deposition uniformity while reducing environmental losses, offering a promising technical solution for the development of intelligent and sustainable plant protection equipment.
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spelling doaj-art-5da94371ce354aba9fdcb55b4ba6cbb82025-08-20T03:12:42ZengFrontiers Media S.A.Frontiers in Plant Science1664-462X2025-07-011610.3389/fpls.2025.16210801621080Orchard variable-rate spraying method integrating GNSS and wind-excited audio-conducted leaf area densityHangxing Zhao0Hangxing Zhao1Hangxing Zhao2Shenghui Yang3Shenghui Yang4Shenghui Yang5Wenwei Li6Wenwei Li7Han Feng8Han Feng9Shijie Jiang10Shijie Jiang11Weihong Liu12Weihong Liu13Jingbin Li14Yongjun Zheng15Yongjun Zheng16Songchao Zhang17Key Laboratory of Modern Agricultural Equipment, Ministry of Agriculture and Rural Affairs, Nanjing, ChinaCollege of Engineering, China Agricultural University, Beijing, ChinaState Key Laboratory of Intelligent Agricultural Power Equipment, Beijing, ChinaKey Laboratory of Modern Agricultural Equipment, Ministry of Agriculture and Rural Affairs, Nanjing, ChinaCollege of Engineering, China Agricultural University, Beijing, ChinaState Key Laboratory of Intelligent Agricultural Power Equipment, Beijing, ChinaCollege of Engineering, China Agricultural University, Beijing, ChinaState Key Laboratory of Intelligent Agricultural Power Equipment, Beijing, ChinaCollege of Engineering, China Agricultural University, Beijing, ChinaState Key Laboratory of Intelligent Agricultural Power Equipment, Beijing, ChinaState Key Laboratory of Intelligent Agricultural Power Equipment, Beijing, ChinaCollege of Agricultural Equipment Engineering, Henan University of Science and Technology, Luoyang, ChinaCollege of Engineering, China Agricultural University, Beijing, ChinaState Key Laboratory of Intelligent Agricultural Power Equipment, Beijing, ChinaCollege of Mechanical and Electrical Engineering, Shihezi University, Shihezi, ChinaCollege of Engineering, China Agricultural University, Beijing, ChinaState Key Laboratory of Intelligent Agricultural Power Equipment, Beijing, ChinaKey Laboratory of Modern Agricultural Equipment, Ministry of Agriculture and Rural Affairs, Nanjing, ChinaIntroductionConventional air-assisted sprayers used in orchards often suffer from excessive pesticide waste, high residue levels, and uneven droplet distribution on fruit tree canopies. Precision spraying technologies have emerged to address these limitations by enabling dynamic regulation of spray parameters according to canopy characteristics. Among these, leaf area density is a key indicator for describing canopy sparseness. However, accurate and automated measurement of canopy leaf area density remains challenging due to leaf shading effects. As a result, few fully functional variable-rate spraying systems have been developed based on this parameter.MethodsThis study presents a variable-rate spraying method that integrates global navigation satellite system (GNSS) positioning with wind-excited audio-conducted estimation of canopy leaf area density. A self-propelled orchard spraying platform was developed to acquire real-time GNSS positioning and audio-conducted canopy leaf area density data. Based on this, a method was established for generating prescription maps that integrate spatial positioning and canopy density information. A variable-rate spray control model and algorithm were then constructed to regulate spray flow according to the spatial distribution of leaf area density across the orchard.ResultsField experiments demonstrated that the system achieved a mean relative error of only 5.52% in spray flow rate regulation. Compared with conventional constant-rate spraying, the variable-rate mode reduced the longitudinal coefficient of variation (CV) of droplet deposition by 55.75% on adaxial leaf surfaces and by 33.22% on abaxial surfaces, with a maximum reduction of 62.32% in transverse CV. Ground runoff of spray solution was reduced by 62.29%, and droplet deposition density on leaf surfaces exceeded 25 droplets/cm², meeting the standard for low-volume insecticide application.DiscussionThe integration of GNSS and wind-excited audio sensing for real-time canopy density assessment enables more precise and efficient pesticide application in orchards. This system significantly improves droplet deposition uniformity while reducing environmental losses, offering a promising technical solution for the development of intelligent and sustainable plant protection equipment.https://www.frontiersin.org/articles/10.3389/fpls.2025.1621080/fullGNSSvariable-rate sprayingleaf area densityprescription mapcanopy droplet deposition
spellingShingle Hangxing Zhao
Hangxing Zhao
Hangxing Zhao
Shenghui Yang
Shenghui Yang
Shenghui Yang
Wenwei Li
Wenwei Li
Han Feng
Han Feng
Shijie Jiang
Shijie Jiang
Weihong Liu
Weihong Liu
Jingbin Li
Yongjun Zheng
Yongjun Zheng
Songchao Zhang
Orchard variable-rate spraying method integrating GNSS and wind-excited audio-conducted leaf area density
Frontiers in Plant Science
GNSS
variable-rate spraying
leaf area density
prescription map
canopy droplet deposition
title Orchard variable-rate spraying method integrating GNSS and wind-excited audio-conducted leaf area density
title_full Orchard variable-rate spraying method integrating GNSS and wind-excited audio-conducted leaf area density
title_fullStr Orchard variable-rate spraying method integrating GNSS and wind-excited audio-conducted leaf area density
title_full_unstemmed Orchard variable-rate spraying method integrating GNSS and wind-excited audio-conducted leaf area density
title_short Orchard variable-rate spraying method integrating GNSS and wind-excited audio-conducted leaf area density
title_sort orchard variable rate spraying method integrating gnss and wind excited audio conducted leaf area density
topic GNSS
variable-rate spraying
leaf area density
prescription map
canopy droplet deposition
url https://www.frontiersin.org/articles/10.3389/fpls.2025.1621080/full
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